Sitting in Scituate, Mass

Photo: Christopher Churchill for The Wall Street Journal

May 26, 2015 12:20 p.m. ET

SCITUATE, Mass.— Susan McDonough used to startle when she awoke at night and saw stained-glassed windows or heard the building around her creak and rattle. But after 10 years, she has grown used to sleeping by her husband in an empty Roman Catholic church every Tuesday.

“I’m trying to save my church,” said Ms. McDonough, a 60-year-old recreation director at a nursing home.

Rather than passively keeping the faith, McDonough though breaking the law, a state court ruled. The Archdiocese of Boston closed St. Frances Xavier Cabrini Church in 2004. A judge said this month that Ms. McDonough and other parishioners are trespassers and ordered them to leave, at a date the court will determine later. The parishioners have filed a motion to suspend the eviction, and the judge could rule as early as Wednesday.

Parishioner Jon Rogers outside St. Frances Xavier Cabrini church which opened in 1961 and has seen generations of the same families attend. Photo: Christopher Churchill for The Wall Street Journal

Eviction would mark the end of a nearly 11-year around-the-clock vigil, conducted in shifts by a group of about 100 parishioners since one of them sneaked in through an open door. It is believed to be the only current occupation of a U.S. Catholic church that has been shut down, said experts who track closures.

“It’s very tragic,” said Sister Christine Schenk, a Catholic nun and co-founder of FutureChurch, a nonprofit that guides congregations faced with closures. “You just wish it didn’t have to come to this.” The Roman Catholic Church says it has little choice but to downsize. While the church is booming in the Southwest and West, buoyed largely by Hispanic immigration, declines in parishioners beset traditional strongholds in the Northeast and parts of the Midwest.

It’s very tragic,” said Sister Christine Schenk, a Catholic nun and co-founder of FutureChurch, a nonprofit that guides congregations faced with closures. “You just wish it didn’t have to come to this.” The Roman Catholic Church says it has little choice but to downsize. While the church is booming in the Southwest and West, buoyed largely by Hispanic immigration, declines in parishioners beset traditional strongholds in the Northeast and parts of the Midwest.

That has led to closures and mergers. Parish advocates say closures aren’t always tied to emptier pews. In some cases, including in the Boston Archdiocese, closures also have been related to financial problems brought on by the sexual-abuse crisis or a shortage of priests.

The number of U.S. Catholic parishes, which includes the U.S. Virgin Islands, dropped to 17,337 in 2014 from 19,559 in 1990, according to the Center for Applied Research in the Apostolate at Georgetown University.

Some congregations have resisted closures, occupying churches with continuous vigils and appealing to the Vatican. But none appears to have lasted as long as the holdouts at St. Frances, stemming from a 2004 archdiocese reconfiguration that closed or merged 77 parishes.

An archdiocese spokesman said that other parishes will welcome the St. Frances faithful, and the parishioners should “conclude the vigil.” Scituate, an affluent seaside town south of Boston, has another Catholic parish, but the St. Frances congregants say both are needed.

Many of the families who joined the church when it opened in 1961 continued to attend for generations, giving the parish particular resonance in many households. For many Catholics, a church is more than bricks and mortar. It is the setting for sacraments such as baptisms and marriages that mark key life events, said Nicholas Cafardi, dean emeritus and a professor of law at Duquesne University School of Law. “Those events make the place sacred,” he said.

A small number of churches were saved through appeals by canon lawyers. Since 2011, 31 U.S. churches have won appeals to the Vatican to remain open or to reopen, according to FutureChurch. St. Frances parishioners lost a Vatican appeal last year, but say they are trying again.

More tensions are brewing. as an Archdiocese of New York reorganization plan would shrink parishes there to 296 from 368 by Aug. 1.